This read-only Counter64 records the number of multicast packets transmitted on the port during this bin's period, per its description, the outbound counterpart to the received-multicast counter. This is useful for confirming that multicast traffic, like an IPTV stream or a routing protocol's multicast hellos, ingested on one port is actually being replicated and forwarded out this specific egress port as expected. An engineer verifying multicast replication to a specific subscriber port would check that this counter increments in line with the expected multicast stream's packet rate during the relevant bins.